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NEW  PERUVIAN  MAMMALS 


BY  WILFRED  H.  OSGOOD. 


The  mammals  described  below  are  those  obviously  new  from  a 
collection  made  during  the  past  year  in  northern  Peru  by  Mr.  M.  P. 
Anderson  and  myself.  Doubtless  there  are  further  novelties,  but  since 
it  is  the  first  considerable  collection  of  middle  Andean  mammals  brought 
to  the  United  States,  this  is  not  readily  ascertained.  A  complete  report 
on  the  entire  collection  is  in  preparation  but  its  publication  is  neces- 
sarily delayed.  Knowledge  of  South  American  mammals  as  yet 
is  so  imperfect  that  no  general  monographic  work  has  been  done  and  in 
many  groups  there  is  much  confusion.  Year  by  year,  however,  the 
task  of  settling  individual  problems  becomes  simpler  and  it  is  to  be 
hoped  that  the  day  is  not  very  remote  when  some  of  the  important 
general  questions  of  distribution  and  relationship  may  be  studied  with 
accurate  and  sufficient  data. 

Peramys  peruvianus  sp.  nov. 

Type  from  Moyobamba.  Peru.  No.  19362  Field  Museum  of  Natural 
History.  Male  adult.  Collected  July  21,  191 2,  by  W.  H.  Osgood  and 
M.  P.  Anderson. 

Characters.  Size  small;  coloration  dark  and  rich;  hair  short  and 
close,  4-5  mm.  long  on  back;  head,  shoidders,  and  back  Vandyke  brown, 
darkening  to  blackish  seal  brown  on  rump;  sides  of  belly  and  entire 
inguinal  region  drabbish  or  broccoli  brown;  median  throat,  chest,  and 
anterior  part  of  abdomen  light  buff  to  bases  of  hairs;  chin  brownish 
drab;  arms,  legs,  and  feet  slightly  darker  than  body. 

Skull  small,  light,  and  devoid  of  angularity;  interorbital  region 
smoothly  rounded  with  only  a  slight  postorbital  protuberance;  nasals 
moderately  expanded  posteriorly,  ending  far  back  of  premaxillae;  last 
upper  molar  greatly  compressed. 

Measurements.  Type:  Total  length  173;  head  and  body  118; 
tail  vertebrae  55;  hind  foot  16.  Skull  of  type  (lacking  posterior  half  of 
braincase):  Zygomatic  breadth  15.3;  nasals  14.5x3.8;  interorbital 
constriction  5.7;  palate  15.2;  front  of  canine  to  back  of  M  *  12.4.     Skull 

93 


94    Field  Museum  of  Natural  History  —  Zoology,  Vol.  X. 

of  female  topotype:  Greatest  length  26.9;  basilar  length  24.5;  zygo- 
matic breadth  14;  nasals  11  X3.2;  interorbital  constriction  5.6;  palate 
13.9;  front  of  canine  to  back  of  M  *  11. i. 

Remarks.  This  species  appears  to  have  no  very  close  relative  unless 
it  be  Peramys  adustus  of  eastern  Colombia  which,  although  about  the 
same  size,  is  evidently  much  paler  in  color  and  lacks  the  extensive 
buffy  pectoral  area.  Both  the  type  and  the  one  topotype  obtained  are 
imperfect,  having  been  injured  by  ants  while  lying  dead  in  the  traps, 
the  latter  so  badly  that  its  mutilated  body  was  preserved  in  alcohol. 

Marmosa  madescens  sp.  nov. 

Type  from  Tambo  Ventija,  10  miles  east  of  Molinopampa,  Peru. 
Altitude  about  9000  ft.  No.  19689  Field  Museum  of  Natural  History. 
Adolescent  male.  Collected  June  15,  1912,  by  W.  H.  Osgood  and  M. 
P.  Anderson. 

Characters.  A  mediimi-sized  species  of  very  dark  color  and  unbeaded 
skull,  probably  allied  to  M.  incana  and  M.  fuscata.  Upper  parts  rich 
dark  brown;  back  Front's  brown  shading  to  Vandyke  brown  on  sides; 
frontal  and  interorbital  region  slightly  paler  brown;  eye  ring  black, 
its  anterior  extension  brownish;  hairs  of  cheeks,  chin,  throat,  breast, 
midventral  and  inguinal  region  self-colored  creamy  buff;  hairs  of  sides 
of  throat  and  belly  and  inner  sides  of  arms  and  thighs  creamy  apically 
and  broadly  slaty  basally;  midventral  area  of  self-colored  hairs  occupy- 
ing about  one-fifth  the  transverse  extent  of  the  abdomen;  tail  thickly 
clothed  with  fine  short  hairs  except  the  distinct  scaly  prehensory  pad; 
upper  side  of  tail  dusky  brownish  except  a  short  variable  white  tip; 
under  side  of  tail  irregularly  whitish  for  distal  two-thirds  of  its  length, 
the  remainder  sooty;  front  of  arms  and  legs  brown;  feet  and  toes  whitish 
at  least  laterally. 

Skull  rather  elongate;  supraorbital  and  temporal  ridges  only  faintly 
indicated;  nasals  slender  and  slightly  expanded  posteriorly. 

Measurements.  Type:  Total  length  259;  head  and  body  120; 
tail  139;  hind  foot  19.  Skull  of  type:  Greatest  length  32.2;  basal 
length  30.9;  zygomatic  breadth  15.7;  least  interorbital  breadth  6.5; 
nasals  14.7  x  3.5;  palate  length  from  gnathion  17.9;  front  of  canine  to 
back  of  M  ^  13.5;  combined  length  of  Ms  ^''  6. 

Remarks.  Although  comparison  of  actual  specimens  has  not  been 
possible,  it  is  evident  that  this  species  has  its  nearest  relationship  with 
M.  incana  and  M.  fuscata.  It  differs  from  fuscata  at  least  in  the  color 
of  its  imderparts  and  doubtless  other  characters  will  be  found  upon 
comparison  of  specimens. 


May,  1913.        New  Peruvian  Mammals  —  Osgood.  95 

Marmosa  musicola  sp,  nov. 

Type  from  Moyobamba,  Peru.  No.  19354  Field  Museum  of  Natural 
History.  Adult  female.  Collected  July  30,  191 2,  by  W.  H.  Osgood 
and  M.  P.  Anderson. 

Characters.  Allied  to  Marmosa  quichua  but  larger,  with  a  longer 
tail ;  blackish  eye  ring  produced  forward  nearly  or  quite  to  end  of  nose ; 
skull  with  well-developed  angtdar  postorbital  processes.  General  color 
of  upper  parts  between  cinnamon  and  russet,  finely  punctulated  with 
dusky;  frontal  and  interorbital  region  very  slightly  paler  than  back; 
eye  ring  sharply  defined  black  extending  forward  to  base  of  whiskers  or 
to  end  of  nose;  under  parts  rich  creamy  buff  or  ochraceous  buff,  the 
hairs  self-colored  on  the  chin,  middle  of  throat,  breast,  and  a  narrow 
midventral  line  —  elsewhere  with  slaty  bases ;  outer  side  of  hind  leg 
dusky  brownish  to  tarsal  joint;  hind  feet  buffy  whitish  on  inner  half, 
pale  hoary  brownish  on  outer  half;  front  of  forelegs  and  at  least  middle 
of  fore  feet  brownish;  tail  brownish,  faintly  and  irregularly  paler  on 
under  side. 

Skull  rather  short,  broad,  and  deep;  braincase  large;  supraorbital 
ridges  beaded  and  forming  a  slight  shelf,  produced  into  distinct  angular 
postorbital  processes;  temporal  ridges  slightly  developed;  nasals  mod- 
erately but  rather  abruptly  expanded. 

Measurements.  Average  of  four  adults  from  the  type  locality: 
Total  length  288  (271-306);  head  and  body  115  (102-129);  tail  vertebrae 
173  (169-175);  hind  foot  18.4  (17-20).  Skull  of  type:  Greatest 
length  33.1;  basal  length  31.9;  zygomatic  breadth  18.3;  breadth  across 
postorbital  processes  7.4;  least  interorbital  breadth  5.7;  nasals  14  x  4.4; 
palate  length  from  gnathion  18. i;  front  of  canine  to  back  of  M  *  12.3; 
combined  length  Ms  ^'^  5.4. 

Remarks.  This  species  seems  to  have  no  nearer  relative  than 
M.  quichua,  with  which  it  agrees  in  its  general  coloration,  but  it  is 
distinguished  by  its  larger  size,  its  lack  of  a  white  tip  to  the  tail,  and 
especially  by  its  angular  postorbital  processes. 

Metachirus  andersoni  sp.  nov. 

Type  from  Yurimaguas,  Peru.  No.  19655  Field  Museum  of  Natural 
History.     Adult  male.     Collected  Sept.  11,  1912,  by  M.  P.  Anderson. 

Characters.  A  richly  colored  species  of  the  opossum  group.  Median 
upper  parts  from  nose  to  end  of  hairy  part  of  tail  rich  brownish  black; 
shoulders  and  sides  of  body  and  rump  grizzled  and  slightly  tinged  with 
buffy ;  front  of  forelegs  and  thighs  buffy  gray ;  fore  and  hind  feet  brownish 


96    Field  Museum  of  Natural  History  —  Zoology,  Vol,  X. 

black;  toes  white;  postocular  spots  buffy  white  sharply  contrasted  with 
surrounding  black ;  under  parts  wholly  ochraceous  buff,  the  hairs  mostly 
self-colored  except  on  the  sides  of  the  neck  and  sides  of  belly  where  they 
have  pale  drab  bases;  dark  and  light  areas  of  scaly  part  of  tail  about 
evenly  divided. 

Skull  large  and  very  elongate;  nasals  pointed  behind  and  extending 
far  beyond  the  posterior  border  of  the  lacrymal  (in  type,  nearly  to 
plane  of  postorbital  processes) ;  jugal  not  greatly  expanded. 

Measurements.  Type  and  adiilt  female  paratype,  respectively: 
Total  length  572,  553;  head  and  body  284,  275;  tail  288,  278;  hind  foot 
40,  35.  Skull  of  type:  Greatest  length  78.8;  zygomatic  breadth  37.9; 
interorbital  constriction  9.3;  width  across  postorbital  processes  13.5; 
nasals  39.6  x  10;  breadth  of  braincase  21.3;  palate  length  from  gnathion 
45.3;  front  of  canine  to  back  of  M  *  31-2;  M  ^  to  M  '  11. 6. 

Remarks.  This  handsome  species  is  evidently  widely  different  in 
color  from  any  previously  described.  Doubtless  its  nearest  relative  is 
M.  opossum  of  Guiana  and  Brazil  from  which  it  is  easily  distinguishable 
by  its  broad  and  sharply  defined  black  dorsal  stripe  and  its  richly  buffy 
tmder  parts. 

Metachirus  canus  sp.  nov. 

Type  from  Moyobamba,  Peru.  No.  19347  Field  Museum  of  Natural 
History.  Male,  young  adult.  Collected  Aug.  4,  191 2,  by  W.  H. 
Osgood  and  M.  P.  Anderson. 

Characters.  A  pale  gray  species  allied  to  M.  grisescens  of  west 
central  Colombia,  but  differing  in  having  a  bicolor  tail,  more  blackish 
upper  parts  and  paler  under  parts.  Upper  parts  uniform  peppery 
gray,  the  hairs  tipped  with  silvery  and  dusky  brownish ;  head  dark  brown 
more  or  less  sprinkled  with  silvery ;  under  parts  pale  cream  buff,  stronger 
anteriorly,  becoming  more  whitish  posteriorly ;  gray  of  sides  encroaching 
largely  on  belly;  feet  pale  drab  proximally,  white  distally;  toes  white; 
slightly  less  than  distal  half  of  tail  white,  remainder  blackish. 

Skull  of  medium  size;  nasals  decidedly  shorter  than  in  M.  grisescens 
and  abruptly  terminated  after  their  moderate  posterior  expansion; 
premaxillae  short,  scarcely  exceeding  posterior  plane  of  canine;  palate 
highly  fenestrate  posteriorly;  maxillary  end  of  jugal  broad  and  deep, 
its  lower  border  practically  parallel  with  the  alveolar  boundary  of  the 
maxillary;  occipital  condyle  decidedly  projected  beyond  inion;  last 
upper  molar  trilobate  in  form,  not  so  regularly  triangular  as  in  related 
species. 

Measurements.     Type:     Total  length  568;  head  and  body  275;  tail 


May,  1913.     New  Peruvian  Mammals  —  Osgood.  97 

293 ;  hind  foot  45.  Skull  of  type:  Basal  length  67.5 ;  occipito-nasal  length 
66.5;  interorbital  constriction  18.9;  nasals  28.8  x  7.2;  palate  length  from 
gnathion  40.2;  front  of  canine  to  back  of  M  ^  20.3;  M  ^  to  M  ^  11.6. 

Remarks.  M.  canus  is  markedly  different  from  all  the  known  forms 
of  the  opossum  series  except  M.  grisescens  from  which  it  differs  in  having 
the  usual  white-tipped  tail  and  in  having  all  its  paler  markings  less 
suffused  with  fulvous.  It  is  perhaps  the  palest  member  of  the  genus, 
whereas  M.  andersoni,  found  at  no  great  distance,  is  the  most  richly 
colored. 

Oryzomys  polius  sp.  nov. 

Type  from  Tambo  Carrizal,  mountains  east  of  Balsas,  Peru.  Alti- 
tude about  5000  ft.  No.  19765  Field  Museum  of  Natural  History. 
Adult  female.  Collected  May  18,  191 2,  by  W.  H.  Osgood  and 
M.  P.  Anderson. 

Characters.  A  large,  long-tailed  species,  of  a  grayish  type  of  colora- 
tion strongly  suggesting  various  United  States  species  of  Neotoma. 
Upper  parts  smoke  gray  tinged  with  fawn  mesially  and  mixed  uniformly 
with  dusky ;  under  parts  grayish  white,  the  hairs  with  slaty  bases  except 
on  the  chin;  eyelids  blackish;  ears  thinly  haired,  blackish;  hands  and 
feet,  with  carpal  and  tarsal  joints,  white;  tail  very  finely  annulated  and 
clothed  with  fine  short  hairs,  white  below  and  on  sides,  dusky  above. 

Skull  rather  elongate;  rostrum  broad  and  heavy  but  relatively  long; 
nasals  long  but  broad;  supraorbital  edges  elevated  and  trenchant, 
continuous  with  parietal  ridges  to  occipito-squamosal  suture;  palate 
with'  deep  lateral  channels  running  from  the  anterior  foramina  to  the 
posterior  lateral  pits  which  are  exceptionally  large  and  deep;  anterior 
palatine  foramina  very  large,  extending  posteriorly  nearly  to  plane  of 
middle  of  first  molar;  mesopterygoid  fossa  obtusely  pointed  anteriorly, 
extending  slightly  beyond  the  posterior  plane  of  the  last  molar;  molar 
teeth  of  moderate  size  and  normal  pattern. 

Measurements.  Very  old  female :  Total  length  352;  head  and  body 
164;  tail  188;  hind  foot  30.  Type:  Total  length  337;  head  and  body 
157;  tail  180;  hind  foot  30.  Skull  of  type  and  very  old  female,  respec- 
tively: Greatest  length  34.7,  37;  basilar  length  27.1,  29.3;  zygomatic 
width  17.8,  19.3;  least  interorbital  width  5.2,  5.8;  nasals  14.2  x  4.2,  1 5.1 
X  4.7;  interparietal  10.2  x  3.4,  9.8  x  4.3;  anterior  palatine  foramina  8.3  x 
3,  9  X  3.7;  postpalatal  length  12.5,  13.5;  upper  toothrow  5.6,  5.4. 

Remarks.  This  species  is  not  closely  related  to  any  with  which  I 
have  been  able  to  compare  it,  and  of  the  numerous  descriptions  of  species 
in  this  genus  I  do  not  find  any  which  seem  to  indicate  that  it  has  received 


gS    Field  Museum  of  Natural  History  —  Zoology,  Vol.  X. 

a  name.  For  convenience  it  might  be  compared  to  O.  xanlhaolus 
which  is  only  slightly  smaller  but  that  species  has  the  usual  more  or 
less  fulvous  coloration  and  the  skull  has  a  different  palatal  and  inter- 
pterygoid  region,  a  shorter  rostrum,  and  various  minor  characters  not 
shown  by  the  present  species.  O.  baroni  appears  to  be  a  sUghtly  differ- 
entiated subspecies  of  xanthaolus. 

Cavia  atahualps  sp.  nov. 

Type  from  Cajamarca,  Peru.  Alt.  9100  ft.  No.  19480  Field 
Museum  of  Natiiral  History.  Female  adult.  Collected  April  14,  191 2, 
by  W.  H.  Osgood  and  M.  P.  Anderson. 

Characters.  Size  large;  color  dark;  allied  to  C.  cutleri  but  much 
darker;  general  color  of  upper  parts  evenly  grizzled  cinnamon  and 
blackish,  the  bases  of  the  hairs  broadly  dark  drab  (15-20  mm.)  followed 
by  two  or  more  annulations  of  cinnamon  and  blackish;  numerous  very 
fine  and  wholly  blackish  hairs  more  or  less  exserted  especially  on  the 
rump  where  they  are  20-50  mm.  long;  sides  and  lateral  under  parts 
only  slightly  paler  than  back;  midventral  region  wood  brown  or  pale 
cinnamon  to  ochraceous  buff  somewhat  broken  b}-  drab  basal  color  on 
belly,  clearer  and  more  dominant  in  pectoral  and  inguinal  regions; 
throat  mixed  cinnamon  and  blackish  scarcely  different  from  upper  parts ; 
chin  and  submaxillary  region  buffy;  fore  and  hind  feet  grizzled  pale 
drab;  ears  thinly  haired,  blackish,  not  contrasted  wdth  svirrounding 
parts;  no  definite  eye  ring. 

Skull  similar  to  that  of  C.  cutleri,  but  audital  bullae  somewhat  larger. 

Measurements.  Type  (  ? ) :  Total  length  275 ;  hind  foot  48.  Topo- 
type  (c?):  Total  length  243;  hind  foot  46.  Sloill  of  type:  Greatest 
length  60;  basilar  length  48.3;  zygomatic  breadth  ^^-j  nasals  19.8  x  8.6; 
diastema  16.2;  palatal  foramina  6;  length  of  toothrow  (alveoU)  14.6. 

Remarks.  As  represented  by  a  specimen  from  Arequipa,  Cavia 
cutleri  is  decidedly  paler  than  the  present  species.  This  difference 
exceeds  possible  individual  variation.  Four  specimens  were  secured 
at  Cajamarca  and  all  are  uniformly  dark  colored,  although  one  immature 
example  shows  somewhat  more  buffy  or  ochraceous  on  the  imder  parts 
than  the  adults.  Various  cranial  differences  are  noticeable  but  the 
only  one  which  is  sufficiently  marked  to  give  promise  of  being  more 
than  an  individual  peculiarity  is  that  of  the  size  of  the  audital  bullae. 

Akodon  mollis  orophilus  subsp.  nov. 

Type  from  six  miles  west  of  Leimabamba,  Peru  (in  mountains  near 


May,  1913.        New  Peruvian  Mammals  —  Osgood.  99 

headwaters  of  Utcubamba  River).  No.  19724  Field  Museum  of 
Natural  History.  Adult  male.  Collected  May  26,  191 2,  by  W.  H. 
Osgood  and  M.  P.  Anderson. 

Characters.  Similar  in  color  and  character  of  pelage  to  Akodon 
mollis  altorum,  but  averaging  slightly  larger  and  more  fulvous  and  having 
marked  cranial  characters.  Skull  compressed  and  attenuate  anteriorly; 
nasals  slender  and  elongate;  zygomatic  plate  short,  having  its  anterior 
edge  convex  and  receding  from  the  base ;  braincase  broader  and  more 
smoothly  rounded  than  in  mollis  and  altorum;  temporal  ridges  practical- 
ly obliterated. 

Measurements.  Type:  Total  length  192;  head  and  body  107 
tail  85;  hind  foot  23.  Skull:  Greatest  length  26.8;  basal  length  24.5 
zygomatic  breadth  13.3;  interorbital  breadth  4.9;  nasals  10.8x2.8 
palatine  foramina  5.8;  diastema  6.8;  upper  molar  series  4.4. 

Remarks.  From  examination  of  an  extensive  series  of  specimens 
representing  localities  from  the  Pacific  coast  to  the  lower  slopes  of  the 
eastern  Andes  of  northern  Peru,  it  is  evident  that  Akodon  mollis  is 
divisible  into  four  easily  recognized  forms.  The  division  is  primarily 
by  cranial  characters  and  secondarily  by  color.  Typical  mollis  of  the 
coast  region  and  altorum  of  the  western  Andes  differ  somewhat  in  color 
and  pelage  but  have  the  same  type  of  skull  as  contrasted  with  orophi- 
lus  of  the  central  Andes  and  orientalis  of  the  upper  montagna  region, 
these  latter  being  likewise  differentiated  by  color  and  dimensions. 
Ecuadorean  specimens  of  altorum  are  not  at  hand,  but  the  statement  in 
the  original  description^  that  they  are  cranially  "as  in  true  mollis '^ 
is  taken  as  sufficient  evidence  that  they  do  not  differ  from  specimens 
from  the  western  Andes  of  Peru  (Cajamarca,  Otuzco,  etc.). 

Akodon  mollis  orientalis  subsp.  nov. 

Type  from  Poco  Tambo,  between  Chachapoyas  and  Rioja,  Peru. 
Altitude  about  6000  ft.  No.  19855  Field  Museum  of  Natural  History. 
Adult  female.  Collected  June  29,  1912,  by  W.  H.  Osgood  and 
M.  P.  Anderson. 

Characters.  Similar  in  cranial  characters  to  A.  m.  orophilus  but 
larger,  longer-tailed,  and  much  darker  in  color.  Upper  parts  deep 
mummy  brown  in  general  appearance,  the  hairs  annulated  with  dark 
umber  and  tipped  with  blackish ;  under  parts  heavily  washed  with  tawny 
russet;  tail  and  feet  entirely  blackish.  Skull  of  the  same  general  form 
and  having  the  slender  rostrum  and  short  receding  zygomatic  plate  as 
in  orophilus,  but  braincase  slightly  broader  and  more  ample. 

1  Thomas,  Ann.  &  Mag.  Nat.  Hist.,  (8),  xi.  p.  404,  April,  1913. 


loo     Field  Museum  or  Natural  History  —  Zoology,  Vol.  X. 

Measurements.  Type:  Total  length  201;  head  and  body  116; 
tail  85;  hind  foot  24.  Skull:  Zygomatic  breadth  13.8;  breadth  of 
braincase  13;  interorbital  breadth  5.5;  nasals  10.6  x  3.4;  palatine  foram- 
ina 5.7;  diastema  7;  upper  molar  series  4.6. 

Remarks.  This  form  is  readily  distinguished  by  its  wholly  black 
tail  and  feet,  the  other  forms  of  A.  mollis  having  grayish  feet  and  a 
bi colored  tail.  These  characters  are  seen  in  their  incipiency  in  speci- 
mens from  localities  immediately  west  of  Poco  Tambo  and  evidence  of 
the  gradation  from  one  form  to  the  other  is  practically  complete.  At 
Poco  Tambo  the  conditions  are  those  of  typical  montagna  with  dense 
himiid  forests,  but  relatively  cool  climate. 


